The sceptical medic

Q It's said that you should do at least three sessions of exercise a week that get you out of breath - but what about yoga and pilates? Don't they count?

A My grandparents, who lived into their 90s, walked every day, stretched, did the gardening and plenty of DIY, and played gentle tennis. Increasingly, evidence appears to support our intuition that sitting for prolonged periods is harmful to our health. Worldwide recommendations have moved from three vigorous workouts to at least 150 minutes of moderately intense activity a week, incurred over most days. Now 300 minutes of activity are considered desirable. In other words, 30-60 minutes, five days a week, which can consist of simply getting up and about, gym work, pilates, sport, cycling, walking to work, taking the stairs, gardening and playing with the kids.

While yoga and pilates are suitable for all ages, the type, duration and intensity of exercise should be tailored to the individual. Younger age groups can consider more intense exercise and manual labour, while the elderly and obese should look at gentler regimes; osteoporosis-risk groups, such as middle-aged women, can use impact training to help bone strength.

Either way, the message is simple. The Japanese model of activity before work, such as yoga, has undoubted benefits. As a society we need to make exercise part of everyday activities. So Brown, Obama et al, build those bike paths and make exercise at the workplace compulsory ... before we get too big to get off the couch.

• Dr Nicholas Peirce is the ECB's chief medical officer and a lead physician for the English Institute of Sport. To ask a question, email osm@observer.co.uk